Improve notification bell placement and change sender to MOPC Portal

- Move notification bell to sidebar header next to logo (desktop)
- Keep bell in mobile header bar (already well-placed)
- Change email sender name from 'MOPC Platform' to 'MOPC Portal'

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/layouts/admin-sidebar.tsx

@@ -170,9 +170,12 @@ export function AdminSidebar({ user }: AdminSidebarProps) {
           isMobileMenuOpen ? 'translate-x-0' : '-translate-x-full'
         )}
       >
-        {/* Logo */}
-        <div className="flex h-16 items-center border-b px-6">
+        {/* Logo + Notification */}
+        <div className="flex h-16 items-center justify-between border-b px-6">
           <Logo showText textSuffix="Admin" />
+          <div className="hidden lg:block">
+            <NotificationBell />
+          </div>
         </div>
 
         {/* Edition Selector */}
@@ -245,10 +248,6 @@ export function AdminSidebar({ user }: AdminSidebarProps) {
 
         {/* User Profile Section */}
         <div className="border-t p-3">
-          {/* Notification Bell - Desktop */}
-          <div className="hidden lg:flex justify-end mb-2">
-            <NotificationBell />
-          </div>
           <DropdownMenu>
             <DropdownMenuTrigger asChild>
               <button className="group flex w-full items-center gap-3 rounded-xl p-2.5 text-left transition-all duration-200 hover:bg-slate-100 dark:hover:bg-slate-800 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring">